Control system for multiple rotor helicopters



J- A. GREEN CONTROL SYSTEM FOR MULTIPLE ROTOR HELICOPTERS Oct. 16, 1951 3 Sheets-Sheet 1 Filed Jan. 4, 1949 INVENTOR.'

Oct. 16, 1951 I .1. A. GREEN 6 CONTROL SYSTEM FOR MULTIPLE ROTOR HELICOPTERS Filed Jan. 4, 1949 3 Sheets-Sheet 2 JOHN A. 6255 IN V EN TOR.

Oct. 16, 1951 A GREEN 2,571,566

CONTROL SYSTEM FOR MULTIPLE ROTOR HELICOPTERS Filed Jan. 4, 1949 5 Sheets-Sheet 5 IN VEN TOR.

ATTORNE Y5 Patented Oct. 16, 1951 CONTROL SYSTEM FOR MULTIPLE ROTOR HELICOPTERS John A. Green, Wakarusa, Ind. Application January 4, 1949, Serial No. 69,202

3 Claims. (Cl. 244-1723) trol of the position of the craft about its transverse horizontal axis.

A further object is to provide a device of this character having a plurality of rotors, each having a plurality of vanes or blades which may be set at any selected pitch required for different operating conditions of the craft.

A further object is to provide a device of this character having three rotors whose vanes are adjustable as to pitch and relatively controllable to control'the operating conditions and the attitude of the craft about its longitudinal axis and about a transverse horizontal axis.

A further object is to provide a helicopter having a plurality of motor-driven rotors so located and arranged that they provide a substantial inherent stability for the craft and constructed to have the vanes thereof adjusted as to pitch,

together with'novel control mechanism for regulating the pitch of the rotors in any manner desired.

Other objects will be apparent from the following specification.

In the drawing;

Fig. 1 is a top plan view of the helicopter.

Fig. 2 is a view of the helicopter in front elevation.

Fig. 3 is an enlarged fragmentary detail sectional View taken on line 33 of Fig. 4.

Fig. 4 is a fragmentary detail sectional view taken on line 44 of Fig. 3.

Fig. 5 is a view of the device in side elevation.

Fig. 6 is an enlarged top plan View illustrating a control system used by the device.

Fig. 7 is a side view of the control system.

Fig. 8 is a front view of the control system.

Referring to the drawings which illustrate the preferred embodiment of the invention, the numeral designates the fuselage of the craft which may be of any suitable size and shape and which mounts therein a suitable power member, such as aninternal combustion engine l2, illustrated schematically in Figs. 1 and and having a drive shaft 1'4. The fuselage is mounted upon ground wheels 16 adjacent its forward end and may have a'downwardly projecting strut l8 adjacent its rear end. A vertical stabilizer panel or element '29 projects from the rear end of the fuselage, and a vertical rudder 22 is pivoted to the rear edge of said stabilizer.

'Laterally projecting hollow housings 24 project from the fuselage in upwardly outwardly inclined position, said parts '24 preferably being located intermediate the longitudinal dimension of the fuselage and being laterally balanced. At their outer end's'the hollow members 24 terminate in substantially cup-shaped upwardly projecting housing parts '25. Bearings 28 are mounted in longitudinal spaced relation in each of the housing parts 24 and serve to journal shafts 30 whose inner ends mount bevel gears 32 which mesh with a bevel gear 34 mounted upon the engine drive shaft.

The outer end of each shaft 38 mounts a beveled pinion '34 positioned to at least partially extend into the housing portion 26.

As best illustrated in Fig. 3, a tubular hub member 35 is suitably journaled as at bearings 38 in the housing part 26 in central position to extend substantially vertical when the fuselage I'll is in its normal attitudefor example, its attitude in normal flight. A bevel gear 40 is fixed upon the hub 36 and meshes with the pinion 34' to be rotated thereby. The tubular member '35 mounts a cross-plate 42 extending perpendicularly thereto at its upper end, and this plate mounts a plurality of sets of bearings 44, the number of sets being equal to the number of 46 are positioned and supported by the bearings 44. and are rotatable about their longitudinal axes within said bearings 44 for purposes to be mentioned hereinafter.

Within the tubular hub 36 is positioned an elongated shaft 48 having a snug but longitudinally slidable fitwithin said hub. The shaft 48 is of greater-length than said hub and, as best illustrated in Fig. 3, the lowerend of said shaft projectsbelow the bottom of the housing part 26,

and the upper end of said shaft projects above the cross-plate 42 and the rotor vanes mounted in the bearin s 44. A cross-arm 50 is fixedly secured to the upper end of the shaft 48, and at its opposite ends and in equispaced relation to the shaft 48 are located transversely projecting rigid pins :52. The pins52 are connected by links 54 With'crank arms 56 fixedly secured to the cylindrical'inner end portion 58 ofeach rotor vane.

rotor.vanes IIIZfto rotateinafpla jativ'e to the longitudinal axis of @III as" will be apparent.;This' iricliriat v V rear rotor introduces both a vertical l n eonipw The control uselage Of the craftfby means df jwhich the pitch or the v nes of theyanou" justedjis best illustrated in 50 constitutes a straight elongated rigid member projecting radially at its ends from the shaft 48,

vided, it will be understood thatqthe member 50 will constitute a rigid spider centered on they member 48 with its arms projecting radially therefrom and equal in number to' the num"-* ber of vanes, and that each of these armswill;

have a connection with one of the rotoryanes. It will also be apparent that where two 'va nesare employed in each rotor, the tilting adjustment thereof will :be equal and-opposites Thisz-will assure the same, anglezzof 1 attack :of 1: each: a of i the -;vanes of a given rotor and; where morethan-two vanes are providediinthe rotor, 'the' construc- -.tion for adjustment f pitch-will; likewise. pro- ;vide equal pitch-angles of each vaneat-all: times.

The shaft 481i5: adapted to rotatewiththe ihub 36 and at itsilower-endmounts a collar :60. having enlarged flangesl62'at its opp sitesendsa Arms 64 encircles the collar L60 andbearingsifi are in-: terposed between said ring andthe flanges I52 ;to 1 accommodate relative rotation of lthe .collar with respectfto thejring; Ajlbellcrankis;pivoted:to

a bracket 58 w carried I by: the ,housing 24 adjacent to the collar.=60, the-pivot axis of ,said bellcrank being designatedbythenumeralflfls one arm 12 A iforwardly upwardly inclined; housing ppr- ,ti0n 82is carried by; the:rear rend-oi? theifuselage a II] and preferably constitutesgan enlargement of qthestabilizer panel :20. A hubfllisjournaled in 7 this housing portion 82 with its;- axis, located in a zver i li plane n li ed orwar ly a d; iii

' iwa d b el v ear. fii sifixd p t f hu wand rneshes;with a bevelgear'BS mounted upon a shaft 90 extending throughpvthe fuselage III in a forward downward directioniiand mounting a pinion-9 2 which meshes with a pinion, 94niounted' upon a longitudinally lextendirigfshaft ss. 't, its dent end,

The shaft qfiimounts a pinion 88 a 11 engine drive a I te .i' I4.. Rotor-vanes. lqzlare'mounted upon the hub [84 andare of rsubs'tantiallylthe same construction .asillu stratedin Fig. wherebythe pitch ofsaid vanes may be varied by me amsmisimilanto I that disclosed in Eigs g and'4 ,Thei inclinedlpo lsitionjof the hub ;84of the frearflrotor causes the ion 6f the nent and a forward propulsion the operation ofjthe craft. ""f

or ent echani s'm located "withinj-tlie constructionillustrated-entails means for individually controlling the pitch ofeaichwaneto achieve a setting-thereof I difierent from' the et- -ting of the other vanes and, alternativelyf may' "2 teratqrtqc up ins su hat be utilized simultaneously to adjust the pitch of the vanes of the two main rotors. The construction illustrated for this purpose entails the mounting of an elongated tube III! in a substantially longitudinally extending position within the craft, as illustrated in Fig. 5, supported by brackets I I2 carried by the fuselage. The brackets '2 permit rotative movement of the tube III! with respect thereto. J A cable H4 has its opposite ends inserted in the ends of the tubular member H0 and passes around a set of four I cases where more t t vanes 45 are p113; or more pulleys II6 journaled about axes fixed withp reference..to the fuselage. The arrangement thus provides a central run I I8 of the cable spaced from the tube IIO. In the preferred embodiment of the invention the tubular member berlocated at the left with respect to the operators seat, in each case as considered by an op- At one of "its ends the tubular memberlm m ount s a ll-shaped member I for longitudinal movement relative ;thereto, said member I 20 bein rk e e qrtheJm mbet,I!! tmac m t such sliding movement and to prevent rotation of t e membea ..1'lat 2;. the; b 1 'll- The ;ends of 'tlie cable IILwithinthetube -I II] are securled to the ends of themember lznat I I I. lThe ifrom the. tube having gear teeth out therein to nember ll;- -inclu des l a-central portion spaced mounts :a member I124inlwhichdsjournaled a stud shaft I26 whose outer end figredly mounts a pinion .;-I 28; which meshes w-ith the rack I22 A bevel pinion ull-is;also fix eduupon theshaft I26 and meshes with bevel .gears I32 journaledupon the ;:ltubular member-MD. "Eachlof these bevel gears I32 has welded orotherwise-fixedly securedthere- -;;to a rigid arm I34 which also is journaled upon ,theltubular memberl I0 and whichl proiects radial1y: therefrom g; As best illustrated: in I Fig. 8, r the armsJM-extend at an angle to each othervas grin an incl ined gdownward direction. Clevices-or t he; fr e'ends of; th l vers 34" and e. inner 1- ends; of the rods 80 are. connected-Vito; saidv clevices. The; complete 'rod -8ll. ;has not; been ,illustrated a 1 herein and it will ,be I understood that; if ,necessary, the part 80; nstead of constituting a single l-rigid-ro d, may; constitute a plurality of rods interisiconnected "through: suitable levers, or v any other construction suitable for transmittingyrocking va moyement;ofztheleveri arms; I341 about, the axis naboutvjan axis: which rispositioned transversely and horizontally in ;the; inormal balanced ,flight a positionof-the'5parts, .which axis is; designated by the numeral I40, a-i'rigidi yoke memberuIfl The -yokewmemberri mounts an 1: upwar lya; xten f .co'ntrol handle or'lever I44 at: its upper: end and a rigid downwardly projectingextensional at its lowergendliuA' clevis-or other fitting-|48 is pivotedzatrthe-xlower end of:- the partJHfi and is mounted :u'pon the front end of a rigid rod I50 or 'rigid 'miiltiple part assemblyawhich extends tofa ldevice similar. to that illustrated in, Fig. 3 for ad- :justing' thepitch of the :vanes: 'I 02 "of the rear .'-rdt0r.-'

In the operation of the :helicopter 'the two main a rotors are caused itorr'otate in opposite directions escapee "so that the .rorc'es exerted i by the wanes-thereof arefully "and equally nounterbaIanced and :l atferal 'sta i1 ity or the crart is inherentl secured. Thus if the "upper mainrotor as viewed in Eigrd,

:is rotating ind counterclockwise d-ire-ct'ion, the lower mai n rr otcr illustrated in th'e same figiire will be bperati'ng in a clockwise dirlefibn as indicated by the arrows in Fig. 1. This arran ement avoids all necessity for changing thefp it'ch of the vanes of the --rotorsat 'd-i li'erentangular pes'itions thereof as has heretofore been required in-helicopters. In-oth'er wordsfthe vanesei the instant rotor maintain the same angle of attach at an times thr'ough each cycle of rotation the-r'eof.

When the vanes are positioned as illustrated in Fig. 1,"so that each blade or each rotor is in the same angular position as the comp'lemen tary blade of the other main rotor at each instant during the rc-tat-iono'f craft, it will be apparent that the moments 'forces exerted in the operation of the device'wi l be --equal -'at all times, assuming that the vanes of the two rotors are set at the same angle of attack. The rear rotor 'is"comparable-'to a conventional'airplane is the ru'dder'22 which is preferably employed but which maybe omitted completely if desired. Where employed, 'it'is'us'e'd "toturn the craft laterally to facilitate sharp changes in direction fa'n'd increases the directional stabuity of the craft. Such changes "indirection, however, may be fnade by the craft even if'th'e 'lllddi 22 is omitted, as

will be desc'ribedhel'i'riafter.

It 'willbe apparentthatthe rear rotdrinay'be adjusted with respect to the pitch setting of its 'duce 1a greater lift than ith'e other. differen'ce iniliftwill cause :the craifttobank about its central longitudinal axis and alsdwill introduce a certain longitudinal turning moment. This turning momentzmayaion'e be sufrlcientto change "the direction or fligl' ltor the bra-ft, although I prefer to use the'rudder ZZ simultaneously with vanes am by manipulating the control handle M4 to either pull or push upon the same. This control handle thus pivots about the axis 14b to either push or pull upon the control rod I50, which movements will respectively increase and decrease the angle of attack or the pitch setting of the vanes I62. Where it is desired to change the pitch of the vanes 46 of one main rotor relative to the other, the control lever I44 is swung from side to side in a manner to rotate the tubular member I H3 in the brackets H2 which journal it. Inasmuch as the rack IZD, I22 is keyed to the tubular member, and the member I24 which journals the shaft E26 is fixed upon the tubular member, it will be apparent that the entire assembly illustrated at the left in Figs. 6 and '7 will swing about the axis of the tubular member I Ill, thereby causing the lever arms I34 to swing equally and in the same direction. This movement will introduce a pushing force upon the rod or rod assembly 83 located at the side of the unit toward which the rocking or swinging motion occurs and Will pull upon the opposite rod or rod unit 80. The two rod units will move equally but oppositely so as to raise the shaft 48 of one of the main rotors and to lower the shaft 48 of the other main rotor, thus causing opposite rotation of the vanes of the two' rotors about their longitudinal axes. It will therefore be apparent that the reaction of the two main rotors in such adjustment will be opposite so that one rotor will have its vanes set in an attitude which will prothe relative adjustment 'o fthe p-it'ch of' t-he vanes of the two mainrotors for "such turningpurposes to increase the control piri'ight direction available to'the o perator o f the craft; 7

In instances where it is desired-to increase or decrease "the pitch of the vanes I 46 :er the two rotors simultaneously and'equally and in the same direction, the hand ley'er 152 pivotedto asuitable "support upon the fuse'lage of the-craft at IM-and having a lower end portion-156 which is connected to the run H 8 or the cable l M, may be moved rerwardl or bacl r wairdly about its pivot axis 154. Movement "of the lever causes inovemen't of the cable in 'a-maIIY-ier to shift the member -[2 0' lengthwise or the'member to. This ioii itudinaiin yement of the member [2 0 relative 'to tnem'emher "I ['8 causes the rack portion ief thereof {to rotate'the pinion I28, the'sh'aft' l 26 and the bevel gear I30. The rotation or the beve'l gear is transmitted by the beve gears 1 32 ine'shing therewith "to "the -lever-arr"n-s 134. inasmuch as the bevel gears 1 32 are journ-aled upon the tube -H 0 and hence are coaxial, and-'further in'asmuch "as they' m'esh with the bevel gear l 3'0-atdiametr ically-opposite points of "the gear [30, the gears "1-32 are caused to rotate in opposite directions. Consequently, rotation of'theg'ear 1-30 in one-direction will cause the lever arms 'l 34 carriedby or secured to gears [32 to swing inwardly toward. each other, while rotation of the gear 1-30 will *cause said "arms to swing oppositely outwardly and away "from each other. "such thatthe lever arms |34are swung an equal The construction is amount *or through an equal arc 'for each rotative movement of the bevel gear 13!]. Thus the arms T34 pullequ'ally upon the rods or rod-units 8'0 "and cause equal and similar adjustment of the setting of the rotor 'blades F6 of the two main rotors, which adjustment occurs -simult-a'neo usly. Thus it -will be apparent that *wherethe craft is hovering and the lift of the vanes is to be'e-it-l'ier increased or decreased to facilitate climbing or descent of the craft, the manipulation of the lever I52 will cause simultaneous adjustment of the pitch of the vanes of the main rotors toproduce the action of the craft desired without disturbing the balance or stability of the craft.

It will be apparent from the foregoing description of the device that an inherently stable craft is provided whose complete control is readily effected by a simple control mechanism adjustable in any of a number of movements to control the lifting reaction of the rotors with the air, to control the longitudinal attitude of the craft, and to control its lateral attitude. Substantially all factors relating to control of the craft in flight are those accommodated by those control means, although as mentioned previously, a direction control rudder 22 may be utilized if desired. In connection with the foregoing it will be understood, of course, that control of the engine will also efiect flight reaction to some degree at least, and separate controls for the engine must be provided.

While the preferred embodiment of the invention has been illustrated and described herein, it will be understood that the construction shown and described is illustrative and is not intended to be limiting, and that other constructions may 

